Display devices and method for manufacturing the same

ABSTRACT

A liquid crystal display is provided. The liquid crystal display includes a first substrate. The liquid crystal display also includes a plurality of first thin film transistors disposed on the first substrate. The liquid crystal display further includes a second substrate disposed opposite to the first substrate. In addition, the liquid crystal display includes a plurality of second thin film transistors disposed on the second substrate. The liquid crystal display also includes a plurality of sensing units disposed on the second substrate, and at least one of the plurality of sensing units electrically connected to at least one of the plurality of second thin film transistors. The liquid crystal display further includes a liquid crystal layer disposed between the first substrate and the second substrate.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of pending U.S. patent applicationSer. No. 16/360,546, filed on Mar. 21, 2019 and entitled “LIQUID CRYSTALDISPLAYS AND METHODS FOR MANUFACTURING THE SAME”, now abandoned, theentirety of which is incorporated by reference herein.

BACKGROUND Technical Field

The present disclosure relates to a liquid crystal display, and inparticular to a liquid crystal display that includes a counter substratewith thin film transistors thereon.

Description of the Related Art

Liquid crystal displays that include a display panel, such assmartphones, tablets, notebooks, monitors, and TVs, have becomeindispensable necessities in modern society. With the flourishingdevelopment of such portable electronic products, consumers have highexpectations regarding the quality, functionality, and price of suchproducts. These electronic products are often provided withcommunications capabilities. Specifically, a liquid crystal display cancontrol the rotation direction of the liquid crystal molecules fordisplaying.

However, some difficulties may be encountered through the use of liquidcrystal displays. Accordingly, a new liquid crystal display thatimproves display quality is needed.

SUMMARY

In accordance with some embodiments of the present disclosure, a liquidcrystal display is provided. The liquid crystal display includes a firstsubstrate. The liquid crystal display also includes a plurality of firstthin film transistors disposed on the first substrate. The liquidcrystal display further includes a second substrate disposed oppositethe first substrate. In addition, the liquid crystal display includes aplurality of second thin film transistors disposed on the secondsubstrate. The liquid crystal display also includes a plurality ofsensing units disposed on the second substrate, and at least one of theplurality of sensing units electrically connected to at least one of theplurality of second thin film transistors. The liquid crystal displayfurther includes a liquid crystal layer disposed between the firstsubstrate and the second substrate.

In accordance with some embodiments of the present disclosure, a methodfor manufacturing a liquid crystal display is provided. The methodincludes providing a first substrate. The method also includes forming aplurality of first thin film transistors on the first substrate. Themethod further includes providing a second substrate. In addition, themethod includes forming a plurality of second thin film transistors onthe second substrate. The method also includes forming a plurality ofsensing units on the second substrate, and at least one of the pluralityof sensing units electrically connected to at least one of the pluralityof second thin film transistors. The method further includes combiningthe first substrate and the second substrate through a liquid crystallayer.

A detailed description is given in the following embodiments withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure may be understood by reading the subsequent detaileddescription and examples with references made to the accompanyingdrawings, wherein:

FIG. 1 illustrates a cross-sectional view of the liquid crystal displayin accordance with some embodiments of the present disclosure.

FIG. 2 illustrates a cross-sectional view of the liquid crystal displayin accordance with some embodiments of the present disclosure.

FIG. 3 illustrates a cross-sectional view of the liquid crystal displayin accordance with some embodiments of the present disclosure.

FIGS. 4A-4C illustrate top views of the liquid crystal display shown inFIG. 3 .

FIG. 5 illustrates a cross-sectional view of the liquid crystal displayin accordance with some embodiments of the present disclosure.

FIG. 6 illustrates a cross-sectional view of the liquid crystal displayin accordance with some embodiments of the present disclosure.

FIG. 7 illustrates a cross-sectional view of the liquid crystal displayin accordance with some embodiments of the present disclosure.

FIG. 8 illustrates a cross-sectional view of the liquid crystal displayin accordance with some embodiments of the present disclosure.

FIGS. 9A-9E illustrate cross-sectional views of different stages of aprocess for manufacturing the liquid crystal display in accordance withsome embodiments of the present disclosure.

FIGS. 10A-10E illustrate cross-sectional views of different stages of aprocess for manufacturing the liquid crystal display in accordance withsome embodiments of the present disclosure.

FIGS. 11A-11E illustrate cross-sectional views of different stages of aprocess for manufacturing the liquid crystal display in accordance withsome embodiments of the present disclosure.

FIG. 12 illustrates a cross-sectional view of the liquid crystal displayin accordance with some embodiments of the present disclosure.

DETAILED DESCRIPTION

The liquid crystal display of the present disclosure and themanufacturing method thereof are described in detail in the followingdescription. In the following detailed description, for purposes ofexplanation, numerous specific details and embodiments are set forth inorder to provide a thorough understanding of the present disclosure. Itwill be apparent, however, that the exemplary embodiments set forthherein are used merely for the purpose of illustration, and theinventive concept may be embodied in various forms without being limitedto those exemplary embodiments. In addition, the drawings of differentembodiments may use like and/or corresponding numerals to denote likeand/or corresponding elements. However, the use of like and/orcorresponding numerals in the drawings of different embodiments does notsuggest any correlation between different embodiments. In addition, inthis specification, expressions such as “first material layer disposedabove/on/over a second material layer”, may indicate the direct contactof the first material layer and the second material layer, or it mayindicate a non-contact state with one or more intermediate layersbetween the first material layer and the second material layer. In theabove situation, the first material layer may not be in direct contactwith the second material layer.

In addition, in this specification, relative expressions are used. Forexample, “upper” or “lower” is used to describe the position of oneelement relative to another. It should be appreciated that if a deviceis flipped upside down, an element that is on the “bottom” will becomean element that is on the “top”.

It should be understood that, although the terms first, second, thirdetc. may be used herein to describe various elements, components,regions, layers, portions and/or sections, these elements, components,regions, layers, portions and/or sections should not be limited by theseterms. These terms are only used to distinguish one element, component,region, layer, portion or section from another element, component,region, layer or section. Thus, a first element, component, region,layer, portion or section discussed below could be termed a secondelement, component, region, layer, portion or section without departingfrom the teachings of the present disclosure.

It should be understood that this description of the exemplaryembodiments is intended to be read in connection with the accompanyingdrawings, which are to be considered part of the entire writtendescription. The drawings are not drawn to scale. In addition,structures and devices are shown schematically in order to simplify thedrawing. In the drawings, some components may be omitted for clarity.Moreover, some components in the drawings may be eliminated as anotherembodiment of the present disclosure.

The terms “about” and “substantially” typically mean +/−20% of thestated value, more typically +/−10% of the stated value, more typically+/−5% of the stated value, more typically +/−3% of the stated value,more typically +/−2% of the stated value, more typically +/−1% of thestated value and even more typically +/−0.5% of the stated value. Thestated value of the present disclosure is an approximate value. Whenthere is no specific description, the stated value includes the meaningof “about” or “substantially”. Moreover, when considering the deviationor the fluctuation of the manufacturing process, the term “same” mayalso include the meaning of “about” or “substantially”.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this disclosure belongs. It should be appreciated that,in each case, the term, which is defined in a commonly used dictionary,should be interpreted as having a meaning that conforms to the relativeskills of the present disclosure and the background or the context ofthe present disclosure, and should not be interpreted in an idealized oroverly formal manner unless so defined.

In addition, in some embodiments of the present disclosure, termsconcerning attachments, coupling and the like, such as “connected” and“interconnected,” refer to a relationship wherein structures are securedor attached to one another either directly or indirectly throughintervening structures, as well as both movable or rigid attachments orrelationships, unless expressly described otherwise.

In addition, the phrase “in a range from a first value to a secondvalue” indicates the range includes the first value, the second value,and other values in between.

In addition, the term “cover” includes the meaning of “cover partially”or “cover completely”.

Refer to FIG. 1 , which illustrates a cross-sectional view of a liquidcrystal display 100A in accordance with some embodiments of the presentdisclosure. The liquid crystal display 100A may include a firstsubstrate 102. The first substrate 102 may include a glass substrate, aceramic substrate, a polymer substrate, other suitable substrates, or acombination thereof. A buffer layer 104 may be disposed on the firstsubstrate 102. The buffer layer 104 may include multiple layers withdifferent materials. A gate dielectric layer 106 may be disposed on thebuffer layer 104. The material of the gate dielectric layer 106 mayinclude, but is not limited to, silicon oxide (SiOx), silicon nitride(SiNy), high dielectric constant (high-k) dielectric material or othersuitable dielectric materials.

As shown in FIG. 1 , the liquid crystal display 100A may include aplurality of first thin film transistors 108. The first thin filmtransistor 108 may include a gate electrode 110, a source 112, a drain114 and a semiconductor layer 116. The gate electrode 110 may bedisposed on the buffer layer 104. In some examples, the thin filmtransistors in the present disclosure may include a top gate thin filmtransistor, a bottom gate thin film transistor, a dual gate thin filmtransistor, a double gate thin film transistor, other suitabletransistors, or a combination thereof.

The material of the gate electrode 110 may include metal, such as copper(Cu), aluminum (Al), molybdenum (Mo), tungsten (W), gold (Au), chromium(Cr), nickel (Ni), platinum (Pt), titanium (Ti).

The source 112, the drain 114 and the semiconductor layer 116 may bedisposed on the gate dielectric layer 106. In some embodiments, thematerial of the semiconductor layer 116 of the first thin filmtransistor 108 may include, but is not limited to, amorphous silicon,polysilicon such as low-temp polysilicon (LTPS), metal oxide or othersuitable materials. The metal oxide may include indium gallium zincoxide (IGZO), indium zinc oxide (IZO), indium gallium zinc tin oxide(IGZTO), low temperature polycrystalline oxide (LTPO), other suitablematerials, or a combination thereof. In some embodiments, the materialof the source 112 and the drain 114 may include metal, such as copper(Cu), aluminum (Al), molybdenum (Mo), tungsten (W), gold (Au), chromium(Cr), nickel (Ni), platinum (Pt), titanium (Ti).

As shown in FIG. 1 , the liquid crystal display 100 may include pads orcontacts (not shown) that are electrically connected to the source 112and/or the drain 114. The pads or the contacts may be used toelectrically connect the first thin film transistor 108 to otherelectronic elements (not shown). The liquid crystal display 100 mayinclude a dielectric layer 120 disposed on the gate dielectric layer106. The material of the dielectric layer 120 may includephosphosilicate glass (PSG), borophosphosilicate glass (BPSG), lowdielectric constant (low-k) material and/or other suitable material(s).The low dielectric constant dielectric materials may include, but arenot limited to, fluorinated silica glass (FSG), silicon oxide, siliconnitride, amorphous fluorinated carbon, parylene, bis-benzocyclobutenes(BCB), polyimides, or other suitable materials. Though it is notdepicted, some metal wires or through holes may be formed in thedielectric layer 120.

As shown in FIG. 1 , the liquid crystal display 100 may include a secondsubstrate 122 that is disposed opposite to the first substrate 102. Thesecond substrate 122 may include a glass substrate, a ceramic substrate,a polymer substrate, other suitable substrates, or a combinationthereof. A buffer layer 124 may be disposed on the second substrate 122.The buffer layer 124 may include multiple layers with differentmaterials. A shielding layer 126 may be disposed on the second substrate122 and/or in the buffer layer 124. In some embodiments, the shieldinglayer 126 may be a light shielding layer that allows specific wavelengthof light or a portion of light to pass through. It should be appreciatedthat although FIG. 1 illustrates the gate electrode 136 is in directlycontact with the shielding layer 126, some additional layers may bedisposed between the gate electrode 136 and the shielding layer 126.

A gate dielectric layer 128 is disposed on the buffer layer 124. Thematerial of the gate dielectric layer 128 may be the same as or similarto the gate dielectric layer 106, and thus it is not repeated herein. Adielectric layer 130 and a dielectric layer 132 may be disposed on thegate dielectric layer 128. The dielectric layers 130 and 132 mayinclude, but is not limited to, PSG, BPSG, FSG, silicon oxide, siliconnitride, amorphous fluorinated carbon, parylene, BCB, polyimides, orother suitable materials. Though it is not depicted, some metal wires orthrough holes may be formed in the dielectric layer 130 and/ordielectric layer 132.

As shown in FIG. 1 , the liquid crystal display 100A may include asecond thin film transistor 134. It should be appreciated that FIG. 1illustrates only one second thin film transistor 134. However, theliquid crystal display 100A may include more second thin filmtransistors 134 in other cross sections. The second thin film transistor134 may include a gate electrode 136, a source 138, a drain 140 and asemiconductor layer 142. The material of the gate electrode 136 mayinclude metal, such as copper (Cu), aluminum (Al), molybdenum (Mo),tungsten (W), gold (Au), chromium (Cr), nickel (Ni), platinum (Pt),titanium (Ti).

The source 138, the drain 140 and the semiconductor layer 142 may bedisposed on the gate dielectric layer 128. In some embodiments, thematerial of the semiconductor layer 142 of the second thin filmtransistor 134 may include, but is not limited to, amorphous silicon,polysilicon such as low-temp polysilicon (LTPS), metal oxide or othersuitable materials. The metal oxide may include indium gallium zincoxide (IGZO), indium zinc oxide (IZO), indium gallium zinc tin oxide(IGZTO), low temperature polycrystalline oxide (LTPO), other suitablematerials, or a combination thereof. In some embodiments, the materialof the source 138 and the drain 140 may include metal.

In the embodiment where the semiconductor layer is the indium galliumzinc oxide (IGZO) layer, the semiconductor layer may include differentcompositions of In, Ga, and Zn, such as 1:1:1:4 or other suitablecomposition(s). In some embodiments, the material of the semiconductorlayer of the first thin film transistor 108 is different from that ofthe second thin film transistor 134. For example, the material of thesemiconductor layer of the first thin film transistor 108 may includelow-temp polysilicon, while the material of the semiconductor layer ofthe second thin film transistor 134 may include IGZO. In other examples,the material of the semiconductor layer of the first thin filmtransistor 108 may include amorphous silicon, while the material of thesemiconductor layer of the second thin film transistor 134 may includelow-temp polysilicon.

In some embodiments, the semiconductor layers 116 and 142 respectivelyinclude a channel. The width and/or the length of the channel of thesemiconductor layer 116 and the channel of the semiconductor layer 142may be different. In some embodiments, the width-to-length ratios of thechannel of the semiconductor layer 116 and the channel of thesemiconductor layer 142 may be different.

In some embodiments, the distance D₁ between the first thin filmtransistor 108 and the second thin film transistor 134 is in a rangefrom about 0.5 μm to about 10 μm. More specifically, the distance D₁between the first thin film transistor 108 and the second thin filmtransistor 134 may refer to a minimum distance between two semiconductorlayers of the first thin film transistor 108 and the second thin filmtransistor 134 along a direction that is parallel to the normal of thefirst substrate 102. For example, the distance D₁ between thesemiconductor layer 116 and the semiconductor layer 142 is in a range ofabout 0.5 μm and about 10 μm. If the distance D₁ between the first thinfilm transistor 108 and the second thin film transistor 134 is withinthe range mentioned above, it may decrease the signal interferencebetween the first thin film transistor 108 and the second thin filmtransistor 134.

In some embodiments, the shielding layer 126 may overlap with thesemiconductor layer 142 of the second thin film transistor 134. In someexamples, the shielding layer 126 may overlap with the channel of thesecond thin film transistor 134. The shielding layer 126 may beconfigured to reduce at least a portion of the light affecting thesecond thin film transistor 134, but it is not limited thereto. The term“overlap” may include partially overlap or entirely overlap in thenormal direction of the second substrate 122. More specifically, theprojection of the shielding layer 126 on the second substrate 122 mayoverlap with the projection of the semiconductor layer of the secondthin film transistor 134 on the second substrate 122.

As shown in FIG. 1 , the liquid crystal display 100A may include pads orcontacts (not shown) electrically connected to the source 138 and thedrain 140. The pads or the contacts may be used to electrically connectthe second thin film transistor 134 to other electronic elements (notshown). The liquid crystal display 100A may further include an electrode146 that electrically connect the second thin film transistor 134 to asensing unit 148. The material of the pad 144 and the electrode 146 mayinclude metal. Though it is not depicted, two or more second thin filmtransistors 134 and sensing units 148 may be disposed on the secondsubstrate 122. The number of second thin film transistors 134 and thenumber of sensing units 148 are not limited in the present disclosure.In some embodiments, at least one of the plurality of sensing units 148may be electrically connected to at least one of the plurality of secondthin film transistors 134. In one example, one sensing units 148 may beelectrically connected to two or more second thin film transistors 134.In other examples, two or more sensing units 148 may be electricallyconnected to two or more second thin film transistors 134. In anotherexample, two or more sensing units 148 may be electrically connected toone second thin film transistors 134. The numbers are not limited in thepresent disclosure.

The sensing unit 148 may be used to sense a photonic signal and convertit into an electrical signal, but it is not limited thereto. In someexamples, the sensing unit 148 may be a touch sensing unit, afingerprint sensing unit, a proximity sensing unit, or any othersuitable sensing unit. Although FIG. 1 illustrates only one sensing unit148, the liquid crystal display 100A may include more sensing units 148,and the scope of the disclosure is not intended to be limited. In someembodiments, the sensing unit 148 may include a photoactive layerdisposed between two semiconductor layers. In addition, these twosemiconductor layers may be doped with dopants of different types. Forexample, one of the semiconductor layers may include n-type dopants, andanother one of the semiconductor layers may include p-type dopants. Insome embodiments, the concentration of the dopants of the photoactivelayer may be less than the concentrations of the dopants of thesemiconductor layers. In some embodiments, the sensing unit 148 may be,but is not limited to, a PIN diode.

As shown in FIG. 1 , the liquid crystal display 100A may include aliquid crystal layer 150 disposed between the second substrate 122 andthe first substrate 102. Though it is not depicted, a pixel electrode, acommon electrode and alignment layers are disposed on the firstsubstrate 102 and/or the second substrate 122. The alignment of theliquid crystal layer 150 may be controlled.

Since some thin film transistors, such as the second thin filmtransistors 134, are disposed on the second substrate 122, the space onthe second substrate 122 may be used in a more efficient way. As aresult, there are fewer thin film transistors occupying space over thefirst substrate 102, thereby reducing the size of the liquid crystaldisplay 100A.

Many variations and/or modifications can be made to embodiments of thedisclosure. Refer to FIG. 2 , which illustrates a cross-sectional viewof a liquid crystal display 100B in accordance with some embodiments ofthe present disclosure. In some embodiments, one of the differencesbetween the liquid crystal display 100A and the liquid crystal display100B is that the liquid crystal display 100B may further include ashielding layer 152 and/or a shielding layer 154. It should beappreciated that the shielding layer 126, the shielding layer 152 and/orthe shielding layer 154 can shield light with specific wavelength, suchas visible light, infrared light (IR) or ultraviolet light (UV). Inanother example, the shielding layer 126, the shielding layer 152 and/orthe shielding layer 154 may include metal material for shieldingelectric field, or include black resin for absorbing light.

As shown in FIG. 2 , the shielding layer 152 may be disposed between thesecond thin film transistor 134 and the liquid crystal layer 150. Insome embodiments, the shielding layer 152 may overlap with thesemiconductor layer 142 of the second thin film transistor 134.Therefore, light may be incident to the sensing unit 148 without beingincident to the second thin film transistor 134, and the second thinfilm transistor 134 may not be affected by the light. In someembodiments, the shielding layer 152 may include a material that canabsorb IR or can shield electric field. In some embodiments, the widthW₁ of the shielding layer 126 may be greater than the width W₂ of theshielding layer 152. The widths of the shielding layers may be measuredalong a direction perpendicular to the normal direction of the secondsubstrate 122 in a cross-sectional view. In some embodiments, thematerial of the shielding layer 126 may be different from the materialof the shielding layer 152.

As shown in FIG. 2 , the shielding layer 154 may be disposed on thefirst thin film transistor 108. In some embodiments, the shielding layer154 may overlap with the semiconductor layer 116 of the first thin filmtransistor 108. Therefore, light may be incident to the sensing unit 148without being incident to the first thin film transistor 108, and thefirst thin film transistor 108 would not be affected by the light.

Many variations and/or modifications can be made to embodiments of thedisclosure. Refer to FIG. 3 , which illustrates a cross-sectional viewof a liquid crystal display 100C in accordance with some embodiments ofthe present disclosure. In some embodiments, one of the differencesbetween the liquid crystal display 100B and the liquid crystal display100C is that the liquid crystal display 100C may include a shieldinglayer 126′ and a sensing unit 148′ replacing the shielding layer 126 andthe sensing unit 148, respectively.

As shown in FIG. 3 , the sensing unit 148′ may extend across two or morefirst thin film transistors 108. More specifically, the sensing unit148′ may overlap with the semiconductor layers of two or more first thinfilm transistors 108. In addition, the shielding layer 126′ may overlapwith the sensing unit 148′. Namely, the projection of the shieldinglayer 126′ on the second substrate 122 may overlap with the projectionof the sensing unit 148′ on the second substrate 122.

Referring to FIG. 4A, which illustrates a top view of the liquid crystaldisplay 100C. It should be appreciated that some elements are omitted inFIG. 4A for clearly presenting the layout of the first thin filmtransistor 108. More specifically, line A-A shown in FIG. 4A is across-sectional line, which presents a cross-sectional view of FIG. 3 .As shown in FIG. 4A, the liquid crystal display 100C may include a dataline 156 and a gate line 158, which may be substantially perpendicularto the data line 156. The data line 156 may be electrically connected tothe source 112 of the first thin film transistor 108. The gate line 158may be electrically connected to the gate electrode 110 of the firstthin film transistor 108. The materials of the data line 156 and thegate line 158 may include metal, such as such as copper (Cu), aluminum(Al), molybdenum (Mo), tungsten (W), gold (Au), chromium (Cr), nickel(Ni), platinum (Pt), titanium (Ti). As shown in FIG. 4A, the data line156 and the gate line 158 may define a plurality of pixels or sub-pixelsof the liquid crystal display 100C.

Referring to FIG. 4B, which illustrates a top view of the liquid crystaldisplay 100C. It should be appreciated that some elements are omitted inFIG. 4B for clearly presenting the layout of the second thin filmtransistor 134, the sensing unit 148′ and the shielding layer 126′. Morespecifically, line B-B shown in FIG. 4B is a cross-sectional line, whichpresents a cross-sectional view of FIG. 3 . As shown in FIG. 4B, theliquid crystal display 100C may include a data line 160 and a gate line162. The data line 160 may be electrically connected to the source 138of the second thin film transistor 134. The gate line 162 may beelectrically connected to the gate electrode 136 of the second thin filmtransistor 134. The materials of the data line 160 and the gate line 162may include metal.

As shown in FIGS. 4A and 4B, the shielding layer 126′ may define aplurality of openings and allow light to pass through the openings. Theshielding layer 126′ may overlap with the data line 160 and the gateline 162 as well as the data line 156 and the gate line 158. The sensingunit 148′ may overlap with two or more first thin film transistors 108.The sensing unit 148′ may extend in a direction that is parallel to theextending direction of the gate line 162. Since the sensing unit 148′has a surface area greater than the surface area of the sensing unit148, the sensing unit 148′ may receive more light, thereby improving thesensitivity of the liquid crystal display 100C.

Many variations and/or modifications can be made to embodiments of thedisclosure. Refer to FIG. 4C, which illustrates a cross-sectional viewof a liquid crystal display 100C in accordance with some embodiments ofthe present disclosure. In some embodiments, the sensing unit 148″ mayinclude at least one protruding portion 148P that extends in a directionsubstantially parallel to the extending direction of with the data line160. In addition, as shown in FIG. 4C, the shielding layer 126′ mayoverlap with the at least one protruding portion 148P. In thisembodiment, the sensing unit 148″ has at least one protruding portion148P, and the sensing unit 148′ would have greater surface area, therebyimproving the sensitivity of the liquid crystal display 100C.

Referring to FIG. 5 , which illustrates a cross-sectional view of aliquid crystal display 200A in accordance with some embodiments of thepresent disclosure. The liquid crystal display 200A includes a firstsubstrate 202. The first substrate 202 may be the same as or similar tothe first substrate 102. The liquid crystal display 200A may include abuffer layer 204 and a gate dielectric layer 206 that may be the same asor similar to the buffer layer 104 and the gate dielectric layer 106,respectively. The liquid crystal display 200A may include a first thinfilm transistor 208. The first thin film transistor 208 may include agate electrode 210, a source 212, a drain 214 and a semiconductor layer216 that may be the same as or similar to the gate electrode 110, thesource 112, the drain 114 and the semiconductor layer 116, respectively.In some examples, the semiconductor layer may include a doped region andan un-doped region. Though it is not depicted, two or more first thinfilm transistors 208 may be disposed on the first substrate 202, and thenumber of first thin film transistors 208 is not limited in the presentdisclosure. The liquid crystal display 200A may include a dielectriclayer 218 and a passivation layer 220. The material of the dielectriclayer 218 and the passivation layer 220 may include dielectric materialssuch as PSG, BPSG, FSG, silicon oxide, silicon nitride, amorphousfluorinated carbon, parylene, BCB, polyimides, or other suitablematerials. As shown in FIG. 5 , the liquid crystal display 200A mayinclude a color filter layer 226 a and a color filter layer 226 bdisposed on the passivation layer 220. The color filter layer 226 a andthe color filter layer 226 b may allow light with specific wavelength topass through. For example, the color filter layer 226 a and the colorfilter layer 226 b may include, but are not limited to, a red colorfilter layer, a green color filter layer, a blue color filter layer oran IR color filter layer. The liquid crystal display 200A may include aplanarization layer 230. The material of the planarization layer 230 maybe the same as or similar to that of the passivation layer 220. In someexamples, the liquid crystal display 200A may include a curved liquidcrystal display or a flexible liquid crystal display. The color filterlayer 226 a and the color filter layer 226 b disposed on the firstsubstrate 202 may reduce the light leakage caused by bending the liquidcrystal display.

As shown in FIG. 5 , the liquid crystal display 200A may include a pixelelectrode 232, a dielectric layer 234 and a common electrode 236. Thepixel electrode 232 is disposed on the planarization layer 230, and thecommon electrode 236 is disposed on the dielectric layer 234. In otherexamples, the pixel electrode 232 may be disposed on the commonelectrode 236, or the pixel electrode 232 and the common electrode 236may be disposed on the same layer, but the present disclosure is notlimited thereto. The voltage difference between the pixel electrode 232and the common electrode 236 may be controlled by the first thin filmtransistor 208 through a conductive through hole 238. The conductivethrough hole 238 may penetrate the planarization layer 230 and the colorfilter layer 226 b. FIG. 5 illustrates that the common electrode 236 ispatterned, and the common electrode 236 would have discrete portions.Many variations and/or modifications can be made to embodiments of thedisclosure. In some embodiments, the common electrode 236 is notpatterned. The material of the pixel electrode 232, the common electrode236 and the conductive through hole 238 may include a metal, atransparent conductive material (e.g. indium tin oxide), or acombination thereof.

The liquid crystal display 200A may include an alignment layer 240. Thealignment layer 240 may be used to control the alignment of the liquidcrystal layer 242. The material of the alignment layer 240 may include,but is not limited to, polyimide (PI). As shown in FIG. 5 , the liquidcrystal display 200A may include a spacer 244 disposed between the firstsubstrate 202 and a second substrate 246. In some embodiments, thematerial of the spacer 244 may include, but is not limited to,polyethylene terephthalate (PET), polyethylene (PE), polyethersulfone(PES), polycarbonate (PC), polymethylmethacrylate (PMMA), glass, anyother suitable materials, or a combination thereof.

As shown in FIG. 5 , the liquid crystal display 200A may include thesecond substrate 246 that may be the same as or similar to the secondsubstrate 122. The liquid crystal display 200A may include a gatedielectric layer 248 that may be the same as or similar to the gatedielectric layer 128. The liquid crystal display 200A may include asecond thin film transistor 250. The second thin film transistor 250 mayinclude a gate electrode 252 a, a gate electrode 252 b, a source 254, adrain 256 and a semiconductor layer 258. In this embodiment, the secondthin film transistor 250 include a double gate thin film transistor thathas two gate electrodes disposed on two opposite sides of thesemiconductor layer of the second thin film transistor 250. In otherexamples, the second thin film transistor 250 may include a top gatethin film transistor, a bottom gate thin film transistor, or a dual gatethin film transistor. In some embodiments, the gate electrode 252 b maybe optionally formed.

The source 254, the drain 256 and the semiconductor layer 258 may be thesame as or similar to the source 138, the drain 140 and thesemiconductor layer 142, respectively. In some embodiments, thematerial(s) of the source 254 and the drain 256 may include metal. Theliquid crystal display 200A may include a sensing unit 264 that may bethe same as or similar to the sensing unit 148. As shown in FIG. 5 , thesecond thin film transistor 250 is electrically connected to the sensingunit 264. Though it is not depicted, two or more second thin filmtransistors 250 and sensing units 264 may be disposed on the secondsubstrate 246. The number of second thin film transistors 250 and thenumber of sensing units 264 are not limited in the present disclosure.The liquid crystal display 200A further includes a dielectric layer 266,a dielectric layer 268. The materials of the dielectric layer 266 andthe dielectric layer 268 may include the dielectric materials mentionedabove.

The liquid crystal display 200A may include an alignment layer 270. Asshown in FIG. 5 , the alignment layer 240 and the alignment layer 270may be disposed on two opposite sides of the liquid crystal layer 242and configured to control the alignment of the liquid crystal layer 242.The material of the alignment layer 270 may include, but is not limitedto, polyimide. The liquid crystal display 200A may include aliquid-emitting region 200LR that may be defined as, but is not limitedto, a region overlapping with the pixel electrode 232.

In this embodiment, the gate electrode 252 a may be used as a shieldinglayer, and light affecting the semiconductor of the second thin filmtransistor 250 may be reduce. Moreover, the color filter layers may bedisposed on the first substrate 202 but not on the second substrate 246.Since some of the thin film transistors, such as the second thin filmtransistors 250, are disposed on the second substrate 246, there is anadditional space that could be used to dispose the color filter layers.Therefore, the space on the first substrate 202 may be used in a moreefficient way. Besides, when the liquid crystal display 200A is a curvedliquid crystal display, the color filter layers disposed on the firstsubstrate 202 may reduce the color shift caused by the mis-alignmentbetween the pixels and the color filter layers.

Many variations and/or modifications can be made to embodiments of thedisclosure. Refer to FIG. 6 , which illustrates a cross-sectional viewof a liquid crystal display 200B in accordance with some embodiments ofthe present disclosure. In some embodiments, one of the differencesbetween the liquid crystal display 200A and the liquid crystal display200B is that the liquid crystal display 200B may further include bufferlayers 272 and 274 disposed on the second substrate 246. The bufferlayers 272 and 274 may be the same as or similar to the buffer layer124. Moreover, the liquid crystal display 200B may include a shieldinglayer 276, a shielding layer 278 and a shielding layer 280. It should beappreciated that the shielding layer 276, the shielding layer 278 and/orthe shielding layer 280 can shield a portion of light including visiblelight or light with specific wavelength, such as infrared light (IR) orultraviolet light (UV). In another example, the shielding layer 276, theshielding layer 278 and/or the shielding layer 280 include a metalmaterial for shielding electric field. In addition, in this embodiment,the liquid crystal display 200B may include the second thin filmtransistor 250 with a single gate electrode, such as a gate electrode252. In the case where the material(s) of the shielding layer 276, theshielding layer 278 and/or the shielding layer 280 include conductivematerial such as metal, the shielding layer 276, the shielding layer 278and/or the shielding layer 280 may not be in contact with otherconductive and/or semi-conductive components, such as the conductivethrough hole 238.

In some embodiments, the shielding layer 276 may be disposed between thesecond substrate 246 and the second thin film transistor 250. As shownin FIG. 6 , the shielding layer 276 overlaps with the semiconductorlayer 258 of the second thin film transistor 250. The shielding layer278 may be disposed between the second thin film transistor 250 and theliquid crystal layer 242. In some embodiments, the shielding layer 278overlaps with the semiconductor layer 258 of the second thin filmtransistor 250.

The shielding layer 280 may be disposed between the first thin filmtransistor 208 and the liquid crystal layer 242. In some embodiments,the shielding layer 280 overlaps with the semiconductor layer 216 of thefirst thin film transistor 208. Moreover, at least a portion of theshielding layer 280 may be disposed between the color filter layer 226 aand the color filter layer 226 b.

As shown in FIG. 6 , the light beam LB from a light source may beincident to the sensing unit 264 while reducing the possibility ofaffecting the first thin film transistor 208 and the second thin filmtransistor 250. In some embodiments, at least one of the shielding layer276, the shielding layer 278 and the shielding layer 280 may beoptionally formed according to the requirement of design. For example,the shielding layer 278 and the shielding layer 280 may not be formed insome embodiments.

In some embodiments, the materials of the shielding layer 276, theshielding layer 278 and/or the shielding layer 280 may be different. Forexample, the shielding layer 280 may include metal material to reflectthe light from the light source. The shielding layer 276 and/or theshielding layer 278 may include a light-absorbing material to decreasethe reflectance of the second thin film transistor 250.

Many variations and/or modifications can be made to embodiments of thedisclosure. Refer to FIG. 7 , which illustrates a cross-sectional viewof a liquid crystal display 200C in accordance with some embodiments ofthe present disclosure. In some embodiments, one of the differencesbetween the liquid crystal display 200B and the liquid crystal display200C is that the liquid crystal display 200C may include a shieldinglayer 282. In some embodiments, the shielding layer 282 may not overlapwith the semiconductor layer 258 of the second thin film transistor 250.In some embodiment, the shielding layer 282 may include an extendingportion of the source 254. That is, the source 254 may include anextending portion disposed on the 268 as a shielding layer. Because ofthe shielding layer 282 and the spacer 244, light from a light sourcemay be incident to the sensing unit 264 while reducing the possibilityof affecting the second thin film transistor 250.

Referring to FIG. 8 , which illustrates a cross-sectional view of aliquid crystal display 300 in accordance with some embodiments of thepresent disclosure. The liquid crystal display 300 includes a firstsubstrate 302. The first substrate 302 may be the same as or similar tothe first substrate 102. The liquid crystal display 300 may include abacklight module 304. The backlight module 304 may include at least onelight source. For example, the backlight module 304 may include aplurality of light-emitting diodes (LED), organic light-emitting diodes(OLED). The light-emitting diodes may be a micro LED or a mini LED. Thebacklight module 304 may include, but is not limited to, direct typebacklight module or edge-lit type backlight module. Some additionallayers may be disposed between the first substrate 302 and the backlightmodule 304, such as a polarizer, but it is not limited thereto.

The liquid crystal display 300 may include a buffer layer 306 and a gatedielectric layer 308 that may be the same as or similar to the bufferlayer 104 and the gate dielectric layer 106, respectively. The liquidcrystal display 300 may include a first thin film transistor 310. Thefirst thin film transistor 310 may include a gate electrode 312, asource 314, a drain 316 and a semiconductor layer 318 that may be thesame as or similar to the gate electrode 110, the source 112, the drain114 and the semiconductor layer 116, respectively. Though it is notdepicted, two or more first thin film transistors 310 may be disposed onthe first substrate 302, and the number of first thin film transistors310 is not limited in the present disclosure. The liquid crystal display300 may include a dielectric layer 322. The material of the dielectriclayer 322 may include the dielectric material(s) mentioned above.

As shown in FIG. 8 , the liquid crystal display 300 may include ashielding layer 324 on the dielectric layer 322. The shielding layer 324may be the same as or similar to the shielding layer 154. The liquidcrystal display 300 may include a color filter layer 326 a and a colorfilter layer 326 b disposed on the dielectric layer 322. FIG. 8illustrates the color filter layer 326 a and the color filter layer 326b are separated from each other. In some examples, the color filterlayer 326 a and the color filter layer 326 b may be partiallyoverlapped. The color filter layer 326 a and the color filter layer 326b may allow light with specific wavelength to pass through. For example,the color filter layer 326 a and the color filter layer 326 b mayinclude, but are not limited to, a red color filter, a green colorfilter, a blue color filter or an IR color filter. The liquid crystaldisplay 300 may include a conductive through hole 328. In someembodiments, the conductive through hole 328 may penetrate the colorfilter layer 326 b and the dielectric layer 322. The conductive throughhole 328 may include conductive material, such as metal or transparentconductive material (e.g. indium tin oxide). The conductive through hole328 may be electrically connected to the first thin film transistor 310.The liquid crystal display 300 may include a planarization layer 332.The material of the planarization layer 332 may be the same as orsimilar to that of the dielectric layer 322.

As shown in FIG. 8 , the liquid crystal display 300 may include a pixelelectrode 330 and a common electrode 336. The pixel electrode 330 may bedisposed on the color filter layer 326 b, and the common electrode 336may be disposed on the planarization layer 332. In other examples, thepixel electrode 330 may be disposed on the common electrode 336, or thepixel electrode 330 and the common electrode 336 may be disposed on thesame layer, but the present disclosure is not limited thereto. Thevoltage difference between the pixel electrode 330 and the commonelectrode 336 may be controlled by the first thin film transistor 310through the conductive through hole 328.

The liquid crystal display 300 may include an alignment layer 334. Thealignment layer 334 may include, but is not limited to, polyimide. Asshown in FIG. 8 , the liquid crystal display 300 may include a spacer339 disposed between the first substrate 302 and a second substrate 340.The material of the spacer 339 may be the same as or similar to that ofthe spacer 244.

As shown in FIG. 8 , the liquid crystal display 300 may include thesecond substrate 340 that may be the same as or similar to the secondsubstrate 122. The liquid crystal display 300 may include a buffer layer342, a buffer layer 344 and a dielectric layer 346 that may be the sameas or similar to the buffer layer 272, the buffer layer 274 and thedielectric layer 266, respectively. The liquid crystal display 300 mayinclude a shielding layer 348 that may be the same as or similar to theshielding layer 126. The liquid crystal display 300 may include a secondthin film transistor 350. The second thin film transistor 350 mayinclude a gate electrode 352, a source 354, a drain 356 and asemiconductor layer 358 that may be the same as or similar to the gateelectrode 136, the source 138, the drain 140 and the semiconductor layer142, respectively. In some embodiments, the material(s) of the source354 and the drain 356 may include metal.

The liquid crystal display 300 may include a sensing unit 364 that maybe the same as or similar to the sensing unit 148. As shown in FIG. 8 ,the second thin film transistor 350 is electrically connected to thesensing unit 364 through the electrode 362. Though it is not depicted,two or more second thin film transistors 350 and sensing units 364 maybe disposed on the second substrate 340, and the number of second thinfilm transistor 350 and/or sensing units 364 is not limited in thepresent disclosure. In some examples, a buffer layer (not shown) or aplanarization layer (not shown) may be disposed between the sensing unit364 and an alignment layer 368, but it is not limited thereto.

The liquid crystal display 300 may include a dielectric layer 366. Theliquid crystal display 300 may include the alignment layer 368. As shownin FIG. 8 , the alignment layer 334 and the alignment layer 368 aredisposed on two opposite sides of the liquid crystal layer 338. Thealignment layer 368 may include, but is not limited to, polyimide. Theliquid crystal display 300 may include a sealant 370, which may bedisposed in the peripheral region of the liquid crystal display 300.

In some embodiments, the distance D₂ between the first thin filmtransistor 310 and the color filter layer (e.g. the color filter layer326 b) overlapping with the first thin film transistor 310 along thenormal direction of the first substrate 302 is less than the distance D₃between the second thin film transistor 350 and the color filter layer(e.g. the color filter layer 326 b) overlapping with the second thinfilm transistor 350 along the normal direction of the first substrate302. More specifically, the minimum distance between the semiconductorlayer 318 of the first thin film transistor 310 and the color filterlayer along the normal direction of the first substrate 302 is less thanthe minimum distance between the semiconductor layer 358 of the secondthin film transistor 350 and the color filter layer along the normaldirection of the first substrate 302.

Referring to FIGS. 9A-9E, which illustrate cross-sectional views ofdifferent stages of a process for manufacturing a liquid crystal display400A in accordance with some embodiments of the present disclosure. Notethat the same or similar elements or layers corresponding to those ofthe liquid crystal display are denoted by like reference numerals. Insome embodiments, the same or similar elements or layers denoted by likereference numerals have the same meaning and will not be repeated forthe sake of brevity.

As shown in FIG. 9A, the first substrate 102 is provided. Next, thefirst thin film transistor 108 may be formed on the first substrate 102as shown in FIG. 9B. The buffer layer 104, the gate dielectric layer106, and the dielectric layer 120 may also be formed on the firstsubstrate 102. Next, the second substrate 122 is provided as shown inFIG. 9C. In some embodiments, as shown in FIG. 9D, the second thin filmtransistor 134 and the sensing unit 148 are formed on the secondsubstrate 122 in accordance with some embodiments. As shown in FIG. 9E,the first substrate 102 and the second substrate 122 are combined, andthe liquid crystal layer 150 is formed between the first substrate 102and the second substrate 122. It should be appreciated thatmanufacturing the liquid crystal display 400A may include forming otherelements. For example, some shielding layers may be formed on the firstsubstrate 102 and/or on the second substrate 122. Some color filterlayers may be formed on the first substrate 102 or the second substrate122. Moreover, the stages of FIGS. 9A and 9B may be performed before,after, or during the stages of FIGS. 9C and 9D.

Referring to FIGS. 10A-10E, which illustrate cross-sectional views ofdifferent stages of a process for manufacturing a liquid crystal display400B in accordance with some embodiments of the present disclosure.

As shown in FIG. 10A, the first substrate 102 is provided, and a firstflexible substrate 170 may be attached to or formed on the firstsubstrate 102. Next, the first thin film transistor 108 may be formed onthe first flexible substrate 170 as shown in FIG. 10B. The buffer layer104, the gate dielectric layer 106, and the dielectric layer 120 mayalso be formed on the first flexible substrate 170. In some embodiments,the first flexible substrate 170 is disposed between the first substrate102 and the first thin film transistor 108. Next, the second substrate122 is provided, and a second flexible substrate 180 may be attached toor formed on the second substrate 122 as shown in FIG. 10C. In someembodiments, as shown in FIG. 10D, the second thin film transistor 134and the sensing unit 148 are formed on the second flexible substrate 180in accordance with some embodiments. In some embodiments, the secondflexible substrate 180 is disposed between the second substrate 122 andthe second thin film transistor 134. As shown in FIG. 10E, the firstsubstrate 102 and the second substrate 122 are combined, and the liquidcrystal layer 150 is formed between the first substrate 102 and thesecond substrate 122. In some embodiments, the first flexible substrate170 and the second flexible substrate 180 are formed between the firstsubstrate 102 and the second substrate 122. It should be appreciatedthat manufacturing the liquid crystal display 400B may include formingother elements. For example, some shielding layers may be formed on thefirst substrate 102 and/or on the second substrate 122. Some colorfilter layers may be formed on the first substrate 102 or the secondsubstrate 122. Moreover, the stages of FIGS. 10A and 10B may beperformed before, after, or during the stages of FIGS. 10C and 10D.

Referring to FIGS. 11A-11E, which illustrate cross-sectional views ofdifferent stages of a process for manufacturing a liquid crystal display400C in accordance with some embodiments of the present disclosure.

As shown in FIG. 11A, the first substrate 102 is provided. Next, thefirst thin film transistor 108′ may be formed on the first substrate 102as shown in FIG. 10B. The buffer layer 104, the gate dielectric layer106, and the dielectric layer 120 may also be formed on the firstsubstrate 102. In some embodiments, the first flexible substrate 170 isformed on the first thin film transistor 108′, and the first thin filmtransistor 108′ would be disposed between the first substrate 102 andthe first flexible substrate 170. The difference between the first thinfilm transistor 108′ and the first thin film transistor 108 is theposition of the gate electrode 110. In other embodiments, the first thinfilm transistor 108′ and the first thin film transistor 108 may be thesame type of thin film transistor. For example, the first thin filmtransistor 108′ and the first thin film transistor 108 both are top gatethin film transistors or bottom gate thin film transistors, but it isnot limited thereto. The first thin film transistor 108 and the firstthin film transistor 108′ may perform the same function.

Next, the second substrate 122 is provided as shown in FIG. 11C. In someembodiments, as shown in FIG. 11D, the second thin film transistor 134′and the sensing unit 148 are formed on the second substrate 122. In someembodiments, the second flexible substrate 180 is formed on the secondthin film transistor 134′. The second thin film transistor 134′ may bedisposed between the second substrate 122 and the second flexiblesubstrate 180. The difference between the second thin film transistor134′ and the second thin film transistor 134 is the position of the gateelectrode 136. The second thin film transistor 134 and the second thinfilm transistor 134′ may perform the same function. In otherembodiments, the second thin film transistor 134′ and the second thinfilm transistor 134 may be the same type of thin film transistor. Forexample, the second thin film transistor 134′ and the second thin filmtransistor 134 both are top gate thin film transistors or bottom gatethin film transistors, but it is not limited thereto. Moreover, thestages of FIGS. 11A and 11B may be performed before, after, or duringthe stages of FIGS. 11C and 11D.

As shown in FIG. 11E, the first flexible substrate 170 and the secondflexible substrate 180 are combined, and the first substrate 102 and thesecond substrate 122 may be removed. In some embodiments, the first thinfilm transistor 108′ and the second thin film transistor 134′ are formedbetween the first flexible substrate 170 and the second flexiblesubstrate 180.

Refer to FIG. 12 , a liquid crystal display 500 is provided. In someembodiment, the liquid crystal display 500 may include a flexible liquidcrystal display, a touch liquid crystal display, a curved liquid crystaldisplay, a tiled display or other suitable displays. For example, theliquid crystal display 500 is a curved liquid crystal display. When theliquid crystal display 500 is bended to form a curved liquid crystaldisplay, the alignment of some of the components (e.g. the color filterlayer or the shielding layer) of the liquid crystal display 500 may beshifted. Therefore, some of the components (e.g. the color filter layerand/or the shielding layer (not shown)) disposed on the second substrate122 originally may be moved to be disposed on the first substrate 102 toreduce the shift. The space of the second substrate 122 may besufficient to dispose sensing unit 148′ and the second thin filmtransistor 134.

Although some embodiments of the present disclosure and their advantageshave been described in detail, it should be understood that variouschanges, substitutions and alterations can be made herein withoutdeparting from the spirit and scope of the disclosure as defined by theappended claims.

What is claimed is:
 1. A display device, comprising: a first substrate;a plurality of first thin film transistors disposed on the firstsubstrate; a second substrate disposed opposite to the first substrate;a plurality of second thin film transistors disposed on the secondsubstrate; a plurality of sensing units disposed on the secondsubstrate; a first shielding layer disposed between at least one of theplurality of sensing units and the first substrate, wherein at least oneof the plurality of first thin film transistors comprises a firstsemiconductor layer, and the first shielding layer overlaps with thefirst semiconductor layer; and a second shielding layer disposed betweenthe first shielding layer and the at least one of the plurality ofsensing units, wherein at least one of the plurality of second thin filmtransistors comprises a second semiconductor layer, and the secondsemiconductor layer overlaps with the second shielding layer, whereinthe first semiconductor layer comprises a first channel, the secondsemiconductor layer comprises a second channel, and a width-to-lengthratio of the first channel is different from a width-to-length ratio ofthe second channel, wherein the first shielding layer comprises aplurality of first openings, the second shielding layer comprises aplurality of second openings, and each of the sensing units overlaps atleast one of the plurality of first openings and at least one of theplurality of second openings.
 2. The display device according to claim1, wherein at least one of the plurality of second thin film transistorsat least partially overlaps with at least one of the plurality of firstthin film transistors in a top view direction of the display device. 3.The display device according to claim 1, wherein the first shieldinglayer is disposed between the second substrate and at least one of theplurality of first thin film transistors.
 4. The display deviceaccording to claim 1, further comprising a third shielding layerdisposed between the second substrate and at least one of the pluralityof second thin film transistors.
 5. The display device according toclaim 1, wherein a distance between a semiconductor layer of at leastone of the plurality of first thin film transistors and a semiconductorlayer of at least one of the plurality of second thin film transistorsis in a range between 0.5 μm and 10 μm.
 6. The display device accordingto claim 1, wherein a material of the first semiconductor layer isdifferent from a material of the second semiconductor layer.
 7. Thedisplay device according to claim 1, wherein at least one of theplurality of sensing units extends across at least two of the pluralityof first thin film transistors.
 8. A method for manufacturing a displaydevice, comprising: providing a first substrate; forming a plurality offirst thin film transistors on the first substrate; providing a secondsubstrate; forming a plurality of second thin film transistors on thesecond substrate; forming a plurality of sensing units on the secondsubstrate; forming a first shielding layer between at least one of theplurality of sensing units and the first substrate, wherein at least oneof the plurality of first thin film transistors comprises a firstsemiconductor layer, and the first shielding layer overlaps with thefirst semiconductor layer; forming a second shielding layer between thefirst shielding layer and the at least one of the plurality of sensingunits, wherein at least one of the plurality of second thin filmtransistors comprises a second semiconductor layer, and the secondsemiconductor layer overlaps with the second shielding layer, whereinthe first semiconductor layer comprises a first channel, the secondsemiconductor layer comprises a second channel, and a width-to-lengthratio of the first channel is different from a width-to-length ratio ofthe second channel, wherein the first shielding layer comprises aplurality of first openings, the second shielding layer comprises aplurality of second openings, and each of the sensing units overlaps atleast one of the plurality of first openings and at least one of theplurality of second openings; and combining the first substrate and thesecond substrate.
 9. The method according to claim 8, furthercomprising: providing a first flexible substrate on the first substrate,the plurality of first thin film transistors being disposed between thefirst flexible substrate and the first substrate; and providing a secondflexible substrate on the second substrate, the plurality of second thinfilm transistors being disposed between the second flexible substrateand the second substrate.
 10. The method according to claim 8, whereinthe first shielding layer is disposed between the second substrate andat least one of the plurality of first thin film transistors.